The specific aims are: To establish an accurate neuropathological diagnosis on all brains submitted to the ADRC Tissue Resource Center; To submit a standardized report, clinicopathological correlation and interpretation of findings to the Clinical Core; To prepare tissues in a standardized manner for use by qualified investigators in the Massachusetts ADRC and other investigators in the field of AD; To prepare tissue microarrays representing distinct groups of diseases or anatomical areas for use by investigators in the ADRC; To establish the degree of RNA preservation in the tissues stored in the Bank; To maintain the Tissue Resource Center as a source of brain tissue for investigators studying AD; To develop and enlarge upon cooperative ventures with the Udall Parkinson Center at the MGH and the Harvard Center for Neurodegeneration; To facilitate correlative studies (including NACC) of pathology with clinical, behavioral, anatomic, genetic, imaging and neurochemical aspects of AD; and To provide a resource for the training and education of future investigators in the neuroanatomy and neuropathology of dementing disorders.